Stress and the city: How your brain responds

The people, the traffic, the crime - these are just some reasons why you might feel stressed out while living in a city. And now research backs up that the brain of a city-dweller may respond more strongly to stress than a country-dweller.

The study in the journal Nature also suggests that two brain regions involved with emotion and stress regulation could potentially be harmed by living in a city.

The new research delves into possible biological explanations for why other studies have found a 21% higher risk of anxiety disorders and a 39% increased risk for mood disorders among people who come from cities.

In the first stage of the study, 32 healthy participants did arithmetic tasks under time pressure while researchers examined their brains using functional magnetic resonance imaging (fMRI). They found that people who live in cities had increased activity in the amygdala, an almond-shaped region of the brain involved in stress response, compared with those who lived in towns and rural areas.

In a follow-up, 23 participants engaged in slightly different mental tasks and got negative feedback from the experimenters in videos. Here, the study authors found the same pattern in amygdala activity among people who lived in cities. At the same time, people who had grown up in cities often showed activity in the perigenual anterior cingulate cortex - a major player in stress regulation. Study authors then looked at 24 people who mostly resided in towns and rural areas, who did not show these stress responses. (This sample size is considered respectable in the brain imaging world).

The brain regions identified here have long been known to activate under stressful conditions, but this is the first evidence that city living can make you respond to stress more, said David Knight, assistant professor of psychology at the University of Alabama, Birmingham, who was not involved in the study.

More research needs to be done to determine whether these brain responses among people who live in cities, or grew up in them, are actually good or bad for you, Knight said.

This study did not directly address how long you have to live in a city to have these effects, or how much vacation time the test subjects take away from busier environments.

There's good evidence that too much stress can harm the brain, Knight said. On the other hand, if you're in a place where you need to react more quickly and vigorously to potential threats, the stress response could be beneficial.

"Maybe just being in a busier environment, things that are stressful are the ones that need to be prioritized. So your brain responds more to stressful events so that you prioritize them more," he said.